Rain 4 G uncapped

I Initially enjoyed rain as its affordable for good internet, I installed a signal booster on my modem to ensure I have full signal.

But for the last month or so, The signal is still full all the time but the web speed run between 0.01 - 1 MBPS Its normally runs like that during the evening but has started during the day .

I left 4 complaints at customer service bit with nou reply. Only get reply saying it has been closed ., I dont know why this is happening but would really like it cleared up.