What do you mean by topup?
Cash credit topup, membership purchase, add-on purchase?
What does your My 48 page say about your current membership status, expiry date, allowance balances#
Does it list a "next" membership which is stacked to kick in when your current membership expires?
Remember that buying a new membership doesn't give you that membership's allowances immediately if you have a current membership that has not yet expired.
All memberships always run their full monthly course and buying a new membership does not terminate a current membership early and start the new one.
If you have used up membership allowances before the membership month is up then you need to buy add-ons and not a new memebrship.
Hope this helps.