Best deals for contract extension

hi, my contract can now be extended, and I also need a new phone. I found some great offers for new customers but the offers for existing customers are not at all attractive. I may be missing something so thought I’d try here. I see o2 tried to call me today but I’m rarely available to take calls during the day which is why I’m trying here.

Ideally I’d like 5-10gb of data (no more, I’m mostly on WiFi so even that’s too much). Flat rate calls and SMS. A newish and good phone. There’s a nice offer on Galaxy S8 with tablet and o2 M package, but this isn’t available when I go to the contract extension offers.  There are also good deals on iPhones for new customers too. I’d like to keep the total price at around 40-45 euros per month which is what I pay now

Thanks for any help and advice.