Credit Report: How can I increase rating

I have recently gone through a 6 month ordeal with a credit card company who I made a purchase from and then returned the items. I was first told to return the items in store (no invoice sent with items) when I tried I was told I would only get the current sale price even though I used their store issued card they had no way to look up what I payed. I returned home with items called company and asked how to return them again for the full price I was given an address to send them to and about a week later I got the same items back again. After 5 months and at least 30 different people and departments I was finally sent the invoice I asked for and returned the items. In the meantime I was getting collection calls for the balance on said Items and when I explained what was happening I was told to either make a payment which I did or that they would note the account and not to worry about it. At the end I payed the balance in full after being told If I did this I would not get reported to the credit agency for delinquency. Well they reported me and within a few days time I received letters from other creditors (with perfect payment histories) asking If I needed a special payment program because I was in financial trouble or ones lowering my credit line. The issue has been resolved as of today the negative removed from my report with an Im sorry it took this long to settle this and nothing else. Is there anything I can do? (sorry so long)