When I asked over phone if they can scan the whole visible area, a lab employee (I'll keep his name undisclosed) answered that this is indeed what they normally do. So I sent twenty slides back with a note saying "I need full-frame scanning as a standard service. If you can provide it, please consider re-scanning... If you'd like to, you may add them to this CD." I got the order back with a nice letter saying that the preset cropvalue on all of their gates cannot be changed and they decided to unmount my slides and scan them on manual gate that has the lowest cropvalue (which they normally do at extra charge; the letter even had phones of three labs targeted to the professional market that may better meet my demand).
Here it sucked. My meticulously cleaned slides got fingerprints and small scratches all over them. The scans were still not full-frame and now had a lot of dust, other crud and occasional fingerprint traces in them. They had both my home and busuiness phone but didn't call before disassembling the mounts (of course I would say no).