Absoutely, categorically, undeniably, a 757 can not do Glasgow to Orlando without a tech stop for refuelling unless it's damn near empty.
If GlobeSham are telling you otherwise, they are mis-selling and are falling foul of trades description rules. If they are misleading you by specifically saying your 757 flights will go non-stop, ask them to put it in writing; then you have evidence of their mis-selling.
Who would believe anything from them though on past performance.
Stoney