What network are they on?? They might be able to get a subsidised upgrade even on PAYG. What is the maximum budget?? Another £20 would probably get you to the Nokia 2 or the Moto C Plus. If you don't mind import phones,the Redmi/Xiaomi phones are well worth a look too,as they have better specs at the price than many other phones.
Here is a comparison of the Moto C and Nokia 1:
https://www.gsmarena.com/compare.php...&idPhone2=9052
I would go for the Nokia 1 as it ships with the latest version of Android,but in its cut down Go version(which is meant to be more efficient).
Tutuapp 9apps Showbox Also apparently there is a 20% code on eBay which is active later today:
https://www.hotukdeals.com/deals/20-...om-4pm-2950568