British Gas have given you the wrong meter readings - we have 3 electricity meters

I have a problem submitting the electricity meter reading as we have 3 different meters
874 this is the mainmeter
878 this is a secondary meter
879 this we think is an off peak meter
furthermore British Gas have given you the reading for meter 874 and wrongly attributed it to meter 878

the current readings are:
874: 22303
878: 11255
879: 33934

look forward to hearing form you