Absolutely no point in progressing. You'd think that years of experience and every possible qualification would earn you a higher salary than a new starter, you'd be wrong. You'll also be given all the complex jobs which gives you less chance to earn commission. Overall it's just not worth it.
Call out is relentless, soul destroying and criminally underpaid for a skilled tradesman.
Senior staff are expected to take on so much responsibility with endless phone calls from the children they employ who cant do the basics, all the while trying to do their own work.
You might get a salary review once every 2/3 years and by then all the new starters are on the same wage as you.