Telkom unreasonable to their customers as usual

I took out a wi-fi contract with Telkom for 10 gigs per month. A standerd 2 year contract. Data sufficient and no problems. 3 months before the 2 years in the middle of the month I ran out of data. The next month again also about middle of the month, the month before renewal I ran out of data by the 3rd. The moment I got notification my phone rang and guess, yes Telkom with a good deal. I exploded but what can you do. They offered me a good deal for 40 gigs a month, 20 x 20. 3months into the new deal I ran out of data. About 4 months ago 10 gig was enough and now 20 or by extension 40 not enough. Now I see they have a deal of 80 gigs 40 x 40 with same price as current, so I contact them via email to please upgrade me, but as expected they do not come back to you. They want me to run out of data over Christmas. This is the people I have to deal with.