Most definately let them know they are not as expected. I had a similar problem with a made to measure blind, it was poorly made, the material wasn't quite the same and the mechanism didn't work properly. I was told by the seller that as I had ordered online and a made to measure service I could not return them or get a refund. This isn't true.
The Sale of Goods act still stands with regard to custom orders, so make sure you use the wording that you have here, that proves they are not as described/ordered.
The Sale of Goods Act 1979 says that any goods you buy from a trader must be:
- of satisfactory quality
- fit for purpose
- match any description given.
You are entitled to a repair, a replacement or a refund.
Hopefully you will meet with a reasonable seller and get the remedy you want without problem - sorry they didn't arrive as expected.