Answered question
I am level 1 with 250mb upgrade right now. My question is:
Can I replace the 250MB upgrade with 500mb when I get to level 2?
Yes you can and as a reminder when you will reach level 3 as you may know
you will be able to use both update at the same time
Other answers
You need to wait for the next billing cycle
Yes, you'll also be able to use your 250 Mb later.
You can aim for level 2 before the next billing period and apply the 500 MB right away.
Then aim for level 3 for the following month, you will have both 500 MB and 250 MB.
LEVELS (Level - Points required - Reward)
Yes but it will only be effective at the start of your next billing cycle.
At first you will be able to only choose one but later on with the level upgrades, slots will it become available which will make you be able to combine both upgrades.