Too many users is the customers problem...not Vodacom s

Shocking service to a business account. Continually loosing connection to the tower. Logged plenty of calls and complaints as this only happens at the office. Their latest excuse is. Too many users connect to the tower's therefore if I want a better connection I have to purchase a booster at my costs. Apparently its not their fault. I cannot understand why I should be held responsible for their lack of signal towers. We cannot even switch over to another service provider as we are legally bound by contract.