Vauxhall Astra engine management light no filter neck

hi i posted couple of days ago regarding fuel tank...having got a bit more info now and another problem has also occured...basically needed a new fuel tank for my car vauxhall sent a new modified version which came with 3 pipes??? my old tank only used 2 pipes so my mechanic connected the new tank with the 2 old pipes the engine wld start but wld then konk out...he has now put 2 of the new pipes on but cant find a function for the 3rd pipe, having spoken to vauxhall they are now sayin that a filter neck is required so instead of purchasing that part he has tweeked it by cutting one of the pipes and bent something to improvise a filter neck (not a clue about this bit basically so prob not describing it too well)...any how the engine light has come on he put it on the diagnostics cant remember the code it was something like p01070 dont quote me at all on that but it said something like "fuel rich" as the fault...he has decided to order the filter neck (i think this is what the part is called) will this solve the problem?? will it b a problem that he has cut one of the pipes is he able to connect the 3rd pipe...also my revs are on 1000 when idle aswel which is a concern for him..hope someone a)understands what im tryin to explain lol b) can shed some light many thanks