Data usage

Words cannot describe how frustrated I am with this service provider. I have been patient for so many months and wanted to give them a chance but I am so over them. I have a data contact for 10GB day and 10 GB night which I believe it should last me 3weeks at most but it last's for 5 days to be exact. I have raised this issue with the service provider before and the issue was fixed for only 2months which my data lasted for a month. Now we are back to the same issue, I then went into the Alex mall branch to get assistance with no luck I was not assisted with the issue and the lady who helped promised she will call their call centre to find out as to why my data does not last and get back to me this was on on the 26 May 09:22:52 when I went in to buy data for the 3rd time in one month. I went in on the 10th May, 20th May and again on the 26th May to buy 10GB. The lady never called me back, her name is Sharol if I am not mistaken her representative number is CL3. I had left the branch with blind trust hoping she would call me back as promised. I am very disappointed and frustrated with the service provider. I simply cannot wait for this contract to end.