Has anyone ever used Bal PTB stone and tile on a wall?? a customer that i'm doing a job for (a fairly good size one to be fair) has already bought the adhesive from his mate at the local shop. He bought PTB for the floor i'm finishing off this week which has been fine. But now he has bought a load more for his bathroom and en-suite, both for the floor and walls. Now his mate at the shop assured him that it is fine on the walls even though it does state floors on the bag. I'm a fair way into this job so I can't just pull the plug, and I also don't want to upset the customer too much by telling him his mate is wrong (rock and a hard place and all that). What do you guy's reckon, should I use it or risk losing the rest of the job and potentially money i'm already owed?????