Ben,
Atlant are out of business. Your options are to find an approximate match for the existing element by removing it and taking to your local spares supplier (or getting your repairer to do it); or replacing the oven.
Given the reasonable cost of ovens, this is a better bet long term.
To be fair Ben, if R600a has got a few elements left, I’d grab one of each and get a bit more out of it – they’re quite reasonably well made machines and it’s a lot less hassle than the shopping trip!