Cell C poor Fibre

I constantly experience a drop on my fiber that i have with cell c . I call the fiber support line to log a fault just to find out that i pay for a 50m line but only receive 20m , the billing department has me on a 50 but the support have me a 20. I got called back by an HOD Thasveer Denath , who confirmed this and said he would get back to me within 24 hours. This was Monday 05/10 . He gave me his cell nr to call for any help but the nr he cave is invalid.