A supplier who does not want to sell more product

I signed up for a 3 year data contract with a 10GB cap. After running out of data 3 months in a row, I contacted Mobile Talk to upgrade my contract to an uncapped contract, only to be told that the maximum I could increase my data contract to was 15GB. I cannot understand how a supplier cannot want to sell more of it's product to its customers. They were unwilling to try and assist in this regard.<br> <br> I will never support such a business again and as soon as my contract expires I will be cancelling it and switching to a supplier who wants as much of my business as I need.