Ok, thanks for the responses Redvee, Skipcool3 and Cornishsimon.

Londonandy, could you confirm if this was your first even Tesco->Airmiles(Avios.com) transfer please?

From your OP it seems it was your first time, but if you could confirm that 100% I would appreciate it.

Also, did you try calling Avios or Tesco to query if its just a mistake, or if they are willing to do anything about it?