Sowdiverse seeds concern

Has anyone used Sowdiverse for seeds before? I started red and white onion, leeks, chives and jalapeños on 2nd Feb. Only 4 of 10 jalapeños came up. A very small amount of the 50 red onion seeds germinated so far. None of the chives, leeks or white onion have germinated so far. The packs do say 2 to 3 weeks but these seeds are on heat mats and I've seen quicker and better germination with other seed providers before. So I'm a bit worried now as I've bought most of my seeds for the year from Sowdiverse.