Shower won't turn on

We have an electric shower that was fitted back in August last year. It was working fine yesterday and then this morning I went to use it and it won't turn on. The light on the ceiling pull cord comes on but the lights on the shower unit itself do not and the button does not turn the shower on. We're hoping to get someone out to look at it under the warranty but they do charge £80 call out fee if the issue isn't covered under warranty. We cannot afford this at the moment as I'm off long term sick and we can barely afford to pay bills. Does anyone know what could potentially be causing this and if it's more likely to be an issue with the shower (warranty) or more an issue with our electrics? Thanks in advance!