Hi Thanks for your prompt reply, presumably you know you can buy one from Fairphone for £17.95
https://shop.fairphone.com/gb_en/spare-parts/fairphone-3-bottom-module
The other issue is that the usb port may be dirty, I’ve had debris/dust colelct in previous phones and eventually damaged the port when trying to clean them. But a @urs_lesse has said the phone is still under warranty, so if you have not damaged it then it will be covered by warranty.
I have seen a post where similarly someone bought a new module and Fairphone reimbursed them once they had assessed it was a faulty part covered by warranty ~ I’ll see if I can find the post and update this topic with a link.
Whether or not it is a problem due to a debris ridden usb port you may like to protect it in future.
EDIT UPDATE: I just noticed @Incanus has suggested the same option 
And I can see from your quick response that you may have already considered that