How do I replace a fan heater on an 02 Nissan Micra?

Hi, my Nissan Micra 02 plate heater is making a horrendous noise on settings 3 and 4 as well as vibrating too.
It is still working on all settings but I think it needs replacing but cannot see anything on line as to how to do it?

A second hand heater fan on ebay is only £8.99, so if I can find instruction on how to replace I will do it myself.

Thanks

Hutch