Telkom ******** us of our data

I feel so ****** by Telkom. Every time someone donates data for me and it happens i have another data on my phone telkom will stop charging me on the data that i had before the donated one. For example this morning i had plus minus 800MB of donated data that expires in 2months time, i also had 460000Gigs of night surfer data. So instead of being charged on my night surfer for downloading telkom decides to use my donated data. Funny enough this is not the first time it happened. One time i had a Monice bundle that would expire in7days so instead of using the one that expires soon telkom used my donated data now forcing me to finish my donated data b4 the 7days one reaches it expiry date just so i can use it. Now whenever i phone them to complain about this they always say its because u are roaming and my roaming is off so now how can i be roaming when its off. I feel like im being cheated on my data that suppose to last me for a month or so and being forced to use it within a week or so. I even went on their site to chat to an agent this morning she also gave me the roaming excuse and then disconnected me without any help just like their call centre agents