have the camera put down first to check the drain,ie is just a joint leaking a cracked pipe tree roots or the drain has collapsed ,you will then be able to see if it needs to be dug or the drain can be lined without digging.

In my opinion. If liquid sediments were rising up through the paving whilst rodding, or power flushing unblocking techniques were in progress. It would normally suggest that there is a fault in the pipe run. This could be either a collapsed section of pipe, or a fault at one of the collar joints within that specific pipe run.
I would definitely say that there is a fault somewhere on the pipe run.
As I do not know what method was used to unblock the drain, it is difficult to say how severe the problem may be.
Rodding manholes shouldn't normally cause liquid sediment to rise above the surface as the pig end of the rod should only push sediment further down the run of the pipe. If a severe blockage is located, the rods would no longer continue to brake up or push the blockage through, preventing this method in clearing the pipe run.
At this stage, I would then suggest a camera survey of the blockage within the pipe. This would then provide the customer with an indication of the blockage or problem. The correct solution and location to the problem can then be addressed.

If power flushing was used before a camera survey has been completed. There is the possibility that any fault within the pipe (blockage, fracture or collapse) will only add to the pressure already in place. The increased pressure will eventually find its own way out of the blockage, as it has no where else to go. If there was a previous fault or fracture with the pipe run, this technique could also increase the damage at that point of the pipe run. Especially if it is a clay pipe.

My recommendation, if not already been done, is to have a camera survey on the pipe run first to assess where the problem lies and what the problem might be.

I believe that excavation and exposure of the pipe run will be inevitable, with repair work to the fault to be completed to resolve the problem.

Another point to think of, after finding where the fault lies. Is where on the run the responsibility lies. The problem may not be within the boundaries of you're property. It may turn out to be a council issue or possibly an issue for one of you're neighbours to resolve.

Kind regards,
A. Drum
ADBS

As you mentioned that liquid is rising upwards there is no doubt this is not normal and there is clearly a fault with the drains.
The contractor who has suggested digging up the area will not of advised cameras clearly as he will not have them or the tools or means of repairing the pipe via internal lining where as companies like Dino Rod will however there cost will most definitely be more expensive than your contractor.
I think the decision you must make is that if your contractor is to lift the block paving and fix the problem will he be able to guarantee the block paving is reset as well as before it was lifted and experience tells me this wont be the case so I think I would be tempted to bite the bullet and get the bigger companies in who can cover your patio or paving under there insurances.

O dear. Advice of not to dismiss water pipe damage. .
Can cause a sinkhole I have seen what this can cause. Manholes. Gulls that have not been pointed to brick work
Sinkhole is result.
Excavate area. Findings of broken pipe. Cut repair with same size in diameter.
Two plastic collars.
Look in side collars there is a middle of pipe seem.
Break seam with small chisel
To make inside smooth.
Slide each collar over pipe .
Place new piece pipe to repair slid collars over joint to close repair.
There is a joint compound to use.
If left one could look at a sink hole 20 to 30 fthe deep...
Sorry to bare bad news.
For water to pass through wearing course that's evidence of damage.
Solution = investigate. .