Mweb price increase after four days of installation !!! Unfair business practice

Four days after installation the price gets increased! I agreed to a contract where I pay R649 for fibre not even four days since installation I get an email to notify me of an increase. This is unfair business practice. Mweb advertises a deal, I sign up for that deal and four days after installation I am notified of a price increase. I signed up to pay R649 I expect to pay what I signed up for and what was agreed upon. Not fair to hit me with a price increase After four days on an amount I did not agree to . If that was the case I would have gone with another service provider .