Can't get an appointment within 60 days of visa expiry

My visa expires end of March, they stipulate that you must apply within 60 days but I can't get an appointment until the end of Feb, all I want to know is simply if that's ok (due to it not being my fault) but no-one can tell me. Have emailed the premium lounge to see if I can come before but as yet have had no response via email. Also have a PRP app**** for 18mts ago and still NO update despite sending loads of emails, no-one ever replies. Husband and kids are all South African yet for 4 yrs all I've done is battle to stay here.