Smart thermostat compatible with electric boiler

Wondering if anyone can help me as i'm pretty clueless ... also a massive thank you in advance for any info/guidance ... much appreciated! I have a Heatrae Sadia Electromax electric flow boiler which provides wet central heating and hot water supply. It's connected to an ancient Danfloss TP5000Si 5/2 programmable thermostat which i'm wanting to change to a smart thermostat. Can someone recommend a compatible smart thermostat model that would work with my type of boiler? I understand they aren't all that common ... the joys of living in a building with no gas supply. The last heating engineer I had out wasn't very confident with the system and i'm unsure whom to ask for advice. Thanks again!