My contract can't be renewed

I am so disappointed with Cellc I can't believe after their services for almost 14 yr. I've been signing contract with them from 2004 and I've never even missed a payment and today when I request to renew my contract I am told I cannot afford to pay my account. I pay an average of R600 pm and I'm requesting a contract of R379 pm, how is it possible that I cannot afford while I'm paying more every month. I need cellc to tell me what to do exactly must I go and start a new experience with another network? Is this how they treat their loyal customers?