I'm so frustrated with Jet stores

I've had a jet account for years but never have I been so disappointed with the service. I made a payment in April and payment was not recognized on my statement and instead of this amount being deducted from my account it was added on and I am now owing over my limit, I have called so many times and send numerous emails but after months I'm still not getting unassisted. The worse part was one of the consultants telling me I bought for more than the limit and when I asked what ?? They couldn't tell me what. I want to close off this account because the aren't helpful both instores and over the phone.