Fungal ear infection

[CheshireChat]

My mum's cat seems to be constantly suffering with ear infections, she's now had issues on and off since the beginning of summer!

The vet has said it's fungal and she's probably getting it from strays that come in the garden, but none of the treatments tried has managed to fully clear it.

She's had various topical treatments, steroids and antiinflammatories so far.

For context, cat is old (around 17), though otherwise in perfect health and my mum lives abroad so I'm hoping there's something I can get her from over here.

If anyone had anything similar I'd be really grateful if you have any suggestions.