Much depends on the context. Here are some possibilities:
1. Did I tell you about my next door neighbour? She bought a new washing machine even though the old one was still working perfectly well.
2. I don't know what to do about the old lady next door. She's bought a new washing machine, even though the old one was still working perfectly well.
3. I don't know what to do about the old lady next door. She's bought a
new washing machine, even though the old one is still working
perfectly well.
In #1, the speaker presents the incident as complete: it's in the past.
In #2, there's a connection between the incident and the present: buying a new washing machine needlessly is an example of the strange behaviour that worries me. She has probably disposed of the old washing machine.
In #3, as #2, except that she probably still has the old washing machine. (For instance, maybe the new one hasn't been delivered yet.)
MrP