Forget about getting cashback
Rimmers Music has completely reneged on its promise to pay cashback despite the purchase having tracked properly. I am not too upset at losing £7-odd on cashback, as the keyboard I purchased was much cheaper at Rimmers than anywhere else, and their customer service was fine - but if you are making a large purchase, don't budget for getting a penny of cashback.
Expect a fight for your cashback
Purchased keyboard in Nov '16 at 2% cashback. The cashback only tracked at 1% so raised a claim. Initially Quidco refused to follow this up with retailer and closed case. So pushed back on Quidco and they agreed to take up case with Rimmers. It is now Mar'17, and Rimmers have tracked the cashback at 1%, the same as before. I have given up trying to get my full cashback. Quidco have been little help. I have therefore now moved to using TopCashback instead of Quidco.