Did Speccy give you a 5x5 alphanumeric product key ?
If whoever you bought this off or even the previous owner before that had upgraded the machine to Ultimate, then it should have a proper product key to activate it.
Normally it would be on a sticker somewhere on the casing of the machine but if this machine had been upgraded from an earlier or lower version of Win 7, then that key wouldn't activate Ultimate.
On an OEM laptop with its original build, Speccy will give the vendor's generic key which is different to the one on the sticker, but using Slui 3 you can change it to the sticker key which can make life easier if you have to do a repair install with a Win 7 SP1 ISO.
There's no need for reimbursement as the postage is negligible and I buy my DVDs in spools of 50s, so there's plenty left