Hmmm ... 2 bad relays? One yes, but two? Although not improbable, it's unlikely.
Are you running any other high-draw components? The floor heat may be
intermittent because your coach is shutting it down to limit load/amperage when other things are running (furnace/HVAC, rear floor heat, basement heat, electric [vs 'furnace'] hydronic heating, microwave, induction cooktop, etc.). The relays may be fine and your floor is shutting down as designed.
If you still need the relays ...
1. Google the part# exactly as written on the relay. Even if Newmar has them, you'll pay much le$$ sourcing them elsewhere
2.
https://integrityrvparts.com/
3.
https://newpar.newmarcorp.com/instan...cher?mode=body
Good luck