What would you do? Replace BabyJogger or think again

[ShortLashes]

John Lewis have offered me a replacement or giftcard refund for my Baby Jogger City Mini GT after part of the frame split. I wasn't expecting the offer of a refund so am now in a quandary! It's been a great single buggy and I need all terrain as live by a forest. Walk a lot. DS is 17 months and walking but still happy in the Baby Jogger and sleeps in it well. But we are expecting another baby in June so wondering if I should....
A) put the money towards a convertible (but they seem so big and we live up 2 flights of steps and have a smallish boot)
B) get a replacement Baby Jogger and use sling for newborn initially; could get a double second hand if needed later on
C) get a different single buggy which works well with a buggy board as heard they are pretty hopeless with the BabyJogger.
I like the look of Micralites but John Lewis don't sell them and reviews seem mixed about the convertible one.
Any thoughts appreciated!