Home choice billing for stuff returned to them

I order a charm base set at the end of Jan 2015, I immediately asked Home Choice to come pick up their bed as the quality was so bad and the legs did not fit the bed. they picked up the bed after 2 weeks on the 18th Feb and on the 19th I sent them the pick up slip, to date they have credited my account and I mail them every week with the pick up slip to credit my account and no one responds, but they will call me every 2 days to remind me to either pay my account or buy something else, their quality is so poor and bad, why would I want to keep on supporting them, plus their customer services don't know how to deal with these complaints, I want my account sorted asap or I ill take this matter further.