Vodafone D2

[inquisitor]

Afaik those cheap Call'ya bundles mostly come with netlocked phones, which means you can use it with any Vodafone SIM. So that cheap Nokia 1208 should work for your friend.
If the SIM has been lost or is defective or whatever, she could request a replacement if the SIM was registered on her name.
But has your friend ever considered switching to a cheaper provider? With solomo pro she could call and text way cheaper not only within Germany but also abroad (e.g. Canada for 9ct/min).