due to following factors, this is the worst time in last few years to have any application open with uk ba:
-close of PSW visa, so there is a rush of such applications
-50% fee increase from april, so mad rush to avoid that
-maybe olympic visa processing also being done by same caseworkers, atleast the operations people will be the same if not the actual caseworkers
in your case you can email the biometric error mail id for the surname correction follow-up, and wait for the extension approval. obviously you fall in the 25% people who do not make the four week cut-off, but that would be mainly due to surge in applications, not any other reason.
be patient, the timing is sheer bad luck, i have an extn application pending with uk ba too