Payment on completion

If you have her agreement on your price to carry out the works in writing/email , regardless of the time it took you do it, then she is required by law to pay. If not then you have good grounds to take further , best solution is small claims courts for claims under £10k. If she’s adamant on not paying you can decide whether to negotiate somewhere in between what she sees as fair and your price as you have to factor in time and effort costs for small claims to settle. I would put it to her as well that if the job took longer than expected would she pay extra? Sounds like someone wanting something for nothing , a lot about ! My builder need to notified of this also .good luck

I always put a notice that all payments are to be made within 7 days of the date on the invoice or failure to do so would incur further charges and i have never had a problem since. Being in the situation you are in I would explain about overheads ect and its not all profits, if all else fails court would be my next step. I hope this helps and good luck 👍

I have had this same exact issue firstly you don't have to justify your rate if the customer was aware of the exact price before you started and agreed to it and you completed the work as agreed they need to pay you end of.Which is why i tell everyone the exact price before hand and clearly state weather it takes 5 minutes or all day the price stays the same if they don't like it they are welcome to hire someone else this usually works and the odd one who doesn't like it you don't want for a customer anyway,but as far as the legal route send them a letter by registered mail stating clear the original terms of the job including price and that the job has now been completed and you expect full payment within 7 days or you will be making an application to the small claims court but brace yourself for negative feedback

County court is very tricky situation I went went once for a mate of mine who had a bad job done which I rectified and took all evidence to the court the judge threw it out because it was not over £10 k.