I claimed a tax rebate from last tax year. The claim took some time (first they'd ask for A, then when I sent A they asked for B, then C).
Finally, last week I got 3 separate letters in the space of 2 days- one said they had calculated I was due a refund and would receive the calculation shortly, the second set out the calculation and said I'd receive the money shortly and the third contained their cheque.
So if they have already promised a refund I would have expected it well within 6 weeks