502 Error & Payment notifications

I have a Wordpress website that has mostly always run smoothly.In the last 6 months I have consistently received the error message 502 when I login and try to make changes to the site. This is a problem, as I host events and have to change this on a regular basis. I have contacted the host company several times and they do not seem to think there is anything their end that can be done. I am looking for someone who can resolve this.

Secondly, I receive payments on my site for bookings to events. I used to receive an email alert when a booking was made but this has stopped for no apparent reason. I would like this re-instated.

I look forward to hearing your proposals.

website: www.leapmindfulness.com