Same my 100GB became 250GB. Since the beginning of Lockdown it has been 300GBs which was pretty cool.
Only thing is their usage tracker is pretty messed up. On some days I have usage spikes which are impossibly high for my internet connection. For example, I hardly used the internet on the last day of the month, yet my usage was higher than ever, 80GBs for the day.
At one stage I thought maybe it was my WiFi that has been compromised, or that maybe one of my devices had gone rogue with updates etc, but it's definitely none of those things.
Of course if I try to check what type of traffic caused most of the usage, it shows as "64GBs of "unclassified" data.
At first I was thinking this was an intentional thing to make our data run out more quickly, but it's totally random and more likely a glitch on their side that has been going on for at least a few months now.
Not so sure tbh... moved from VDSL to Fibre, and for the first 2-3 months it was basically unusable due to massive (tm) packetloss.
Even now it's offline for a few days or hours a month, every month. Frogfoot is utter shite.