Lebara Making Life Difficult

I have 2 sim cards with Lebara... One for me and one for my wife, both payable from my bank account.
We want to stay with Lebara but also want to alter the arrangement (Keeping it the same) so that my wifes sim card is paid from her own bank account, keeping her same number.
I have contacted Lebara and for some reason this is not a straight forward task. I quote ..."There is a process through which we can remove this number from the current account email. But we have to turn off the auto-renewal for your current plan" and "You will not lose the number but you will just have to purchase new plan and set new payment details again for that number and you have to choose plans from".
We are both currently on 12gb but the new plans they are offering is either 5gb (Too little) or 30gb (Too much) so it looks like I am going to find a new provider.
Why can this not just be a simple transfer??

So both numbers are under 1 account.
Can you not just delete number from your account and get her to link to a new account she setup.

Yes, both numbers are under my account.
I'm a tad worried that if I delete number, its lost for good. The agent I chatted with advised I had to purchase a new plan which is not what I want !!!

I dont think it will it will just disconnect from your account so your wife can add to her account.
Though she can port out to another provider for a month and then come back.

I'm not sure, and Lebara haven't really advised, the best way to progress this situation as they said she would need to take a new deal.
"Though she can port out to another provider for a month and then come back"....... I had thought of that but if she moves, she'll stay with the new provider.
It's Lebaras loss and I'm quite sure they don't care but this to me is something that could be a simple fix.