Decreasing Download Speeds

I have been with Rain for 9 months and has been the best in terms of download speed Ever since two months ago speeds have dropped tremendously. I live in Eerste River and speeds are pathethic (bps-kbps) no more mbps I work in Cape Town CBD and speeds are no longer so over the charts as they used to be (used to be 30-40mbps)

I have used different modems, have restarted them, firmware is all up to date, i am out of ideas

My take is with the more people joining Rain, the infrastructure is becoming more over loaded