Hello B_robin,
Welcome to the community1
If you changed your plan in the middle of billing cycles, I believe you should have access to the larger of the 2 amounts of data for the remainder of the cycle (see here). In your case, you should have access to 60 GB. However, I don't think that is to say you have an additional 60 GB on top of what you have already used from your 40 GB allotment. Your remaining data would be the 60 GB minus the amount of data you have already used from your old plan. You should also note that your monthly charges would be prorated on your next bill.
Hope this helps 😀
Cheers
