"NOTE:
The transaction you sent is spending an unconfirmed transaction consider paying a higher fee if creating many transactions.
This means that we need to wait for one on-chain confirmation for this order. To speed up your order spend all your wallet funds and send funds to yourself with a high fee for faster confirmation."
Obviously this was written by someone who doesn't understand English or possibly they are trying to accuse customers of double spending. Anyway, I'm not creating many transactions... only one.
the bold statement suggests you were spending an input with an unconfirmed parent. were you?
if that is the case, i'm not surprised they required confirmation since it makes confirmation unpredictable.
Fees are higher than normal now.
You said you paid 7sat/byte, which is pretty low. You will have to wait. I don't think they are scammers, they are not forced to accept an unconfirmed transaction.