Rain slowing down network speed

Rain is throttling my data,what that means is they are decreasing my download speed, something ISPs tend to do but rain claims that they don't and if they decided to would give you prior notice which is contradictory if you ask me.

I've been using Rain since February with no problems, first month was great with speeds of up to 5mbps and second and third month 2mbps to 3mbps, I can live with that but this month got even worse when my download speed was less than 500kb and dropping.