Climate blower fan intermittent

I am having problem with my eco sport 2019 auto where the interior fan blower will run on full speed when car first started and is then adjustable for about 2 or 3 minutes to any speed from slow to high but then blower stops and any air flow is then barely pushing air thru the vents (probably from speed of car as opposed to the blower fan) If I switch off and on via heater button sometimes this gives some control back for a bit but mostly not and no further opportunitiy to work for rest of journey.

I have tried swapping relays with a spare but makes no difference - has anybody seen this issue and if so is it related to resister pack or something else.