Game - How RUDE!

Why must Game keep on harassing me to make payment on my account when I made payment when it was due and sent them the proof? Instead they keep sending me letters of demand threatening sms's in capital letters like someone who's account was in arrears for years, really now. They send correspondence with no signature or contact numbers and constantly harass me for what? I have officially had it with their poor service levels and I'm absolutely and utterly disgusted. I'm never shopping there again!