I have noticed, amongst many others, that Wind Data is becoming almost un-usable at certain times. Wind is aggressively promoting plans and offerings, thus attracting customers, without building up their infrastructure to match. This has resulted, in my case anyway, in data rates of a few kbps ( not mbps ) even with full RF signals.
Their Facebook, Tumbler, etc pages are full of customers complaining about almost non-existent data service.
Perhaps the OP is also a victim of this issue, at least in part.