Why didnt the OP check when the decorator first turned up with the materials that the coving was right size,
Why when it was realised by the OP that an incorrect size was being used did the OP allow the work to continue to its end and now complain and withhold payment.
i can understand why the op didnt check before they started.
they are meant to be the so called experts.
few years back i had a couple of doors to hang for a customer,about 4 in total,they had already had some fitted a year or so before,and i noticed that they were upside down.
when i mentioned to the customer about it they were shocked i said what do you want me to do,fit the new 1s the same way or fit them the correct way.
and would you like me to see if i can salvage the others.
no fit them the same way.i wasnt happy but hey they were the customer.