I think you have been mis-sold at least.
If they adverised imperial sizes and you ordered imperial sizes then they should not subsitute metric without your agreement. Again strip is not sheared off sheet.
If it is the obvious supplier then their terms and coditions are very suspect. For example:

“Descriptive matter illustrations, dimensions and weights issued by the company are for guidance only and are not binding. The company reserves the right to alter patterns and designs without prior notice”

Clearly breaches weights and measures legislation. Mind you that also says you must sell in metric  measurements so 1/4″ should be sold as 6.35mm (1/4″).

I’d be talking to Milton Keynes Trading Standards….

Robert.

If you paid by credit card ask them for a refund. Trading standards should look at them. Publish the name here so others do not get caught out as well.

For on-line and distance purchases you have the legal right, within two weeks, of a return for a full refund. A fault does not need to be claimed, although you might not get back the return postage and this seller doesn’t sound too cooperative. Credit card Section 75 protection only applies over £100.

Fawlty Materials?

ManKy Metals😮