What is bad is the fact that I'm getting 1.5Mbps.
There isn't much they can do about it at all.
4x4 mimo on band 38 maxes out at 220Mbps and 4x4 mimo maxes out at 180Mbps give or take. That gives a total of very roughly 400Mbps per tower that has both bands and run both bands in a 4x4 mimo configuration. That is a physical spectrum limitation there is nothing they can do about that unless they are given more spectrum.
Now you factor in distance that slows it down. CPE that might not support 4x4 mimo. Congestion because how many Fixed LTE users, Rain Mobile R250 users and Vodacom customers per Rain tower? Things are going to get pretty slow.
The max above is if the tower is run by Rain and supported by fibre backhaul. Microwave links will likely be slower. Towers only running Band 3 will be worse as they are run by Vodacom and usually only run at 2x2 mimo and is run from the same sector antennas as Vodacom so can't be upgraded. Needs new antennas. Those are also usually microwave backhaul.
It's obviously not ideal but congestion is going to be the order of the day unfortunately so they would need to manage the heavy downloaders unfortunately.
I stand to be corrected though as info regarding max rates aren't that easily available.