If you were on FTTC , and never asked to be removed ( either directly , asking to be ceased , or indirectly by moving or inquiring with another provider ) then you must still have a FTTC port allocated to you in the FTTC cabinet, so when you reported a fault , why were you not simply returned to the port allocated to you and if that port were faulty, the fault repaired.....someone ‘pinching’ your port doesn’t seem likely after all , even if it were a mistake and another customer put onto your port in error , the port that customer should be on will presumably be spare , and the OR fault person could simply put you and that other customer onto the appropriate ports, the ‘system’ won’t allow 2 customers to be allocated the same port, so the question I would be asking is why the need to move you onto ADSL then back onto FTTC when your account should already be FTTC with an allocated port.
I would be asking if you were somehow removed from FTTC , because , ( presumably in error ) a ‘cease’ order was raised for you, removing you from FTTC, but this wouldn’t explain why you couldn’t just be put straight back onto FTTC without the need for ADSL first, if the FTTC cabinet is full, then that could be the reason for ADSL in the interim, but then you wouldn’t know how long before you are moved back onto FTTC ....something doesn’t add up.