As a landlord, this sort of thing (carefully avoids triggering the profanity filter) "really annoys me". Most of the red tape we have to deal with can be traced back to toerags like this LL.
As to all the comments about the landlords' duty to maintain a safe property - but that really doesn't do much "unless something bad happens". One the one hand, if (say) someone got electrocuted then the LL will well and truly stuffed with no get-out - but that's cold comfort for the people involved.
And if the LL is like this, then I can well imagine that they would be open to a revenge eviction - putting the tenants in a difficult position in terms of getting things fixed. If they push it, they risk getting a S21 notice; if they don't then they have to live with dangerous electrics.
It could be useful if the tenants got evidence that the landlord says it's all OK - whether that's asking his by text and getting an answer, or email, or a recording of a conversation. Then if they were to get their own EICR from the OP showing that the electrics are dangerous, then they stand a reasonable chance of getting the council to take interest.
But at the end of the day, perhaps the tenants need to consider whether they want to carry on living in a property with a LL like that. Painful (and potentially expensive) though that decision might be to make.
Unfortunately for tenants, the landlords have the upper hand in most areas - there being more tenant demand than properties to meet it. So moving may not be an easy option.