I thought people might be intersted in my experience with Maplin.
I bought a satellite kit from their website using Paypal, but when it arrived it was a different type. I specifically wanted the one described. I rang and explained and arranged for them to collect it and refund my money. They collected it but no refund arrived. Each time I rang they said it would be done "at the end of the week" or "the engineers need to check the item is not damaged" or "we have to issue a cheque and that takes time (no refund via Paypal)".
Eventually (at 44 days after the purchase) I filed a dispute with Paypal. Maplin refunded via Paypal within the hour.
Maybe Paypal disputes get dealt with by a different department, but whatever the reason it worked where regular phone calls and emails failed to get anywhere for 6 weeks.
Robert