Anyone know of a sewage removal company as our tank here in Lamphun is near full ?

The local tesabahn will have a service.

If you ring their general number they should be able to give you details to contact the service for sewage.

Sorry if you mean full of solids but tanks should always be nearly full - they are designed that way - only spill overflow to drain field. Normally operating system should not require pumping (unless it is just a container). Expect our neighbors would be best source of information - here in Bangkok the government has trucks to do this and much safer than having a private firm do (private firms will always charge as much as they can - done to everyone not just foreigners).

You need someone to pump? We have someone come monthly. Can give you phone number if you need.