Presumably this is linked to your other question about £7.00p per hour offer in the Ad.
The answer to that bit is that the Ad is just an Ad - it is what is agreed in the contract that counts - she must have received a letter of some sorts confirming the appointment, which ought to say the salary, or at least the band / spine point to start on - that is aligned to a published salary scale.
Now then, this business about a 12 month break in service. Please explain further. Did she leave / was dismissed before? - or was this 'break in service' something agreed formally between her and her employer - that she could come back and her restart in service would be regarded as a continuity of her existing contract? Otherwise, it's effectively a new employment and a new contract, I reckon.