Tiger loop - Oil flow from tank to boiler?

I had a replacement oil tank fitted in May and because of current legislation not being about when the initial tank was fitted, the new one had to be placed further away from the house.

The tank is at a lower level than the boiler meaning the oil needs to travel in a pipe that slants upwards and uphill. The boiler is probably about 2 feet higher than the tank oil outlet.

The installer quoted a price that stated amongst other items "removal of old system and recommission of the new system, test for working." We accepted and had the work done.

Once complete the installer tested the boiler fired for a few minutes, hence the presence of oil, then mentioned that everything seems fine but the system might need a piece of equipment (I now know this to be a tiger loop), near to where the pipe enters the connection to go into the house, then to the boiler , and I guessed this piece of equipment would have a 'drawing of oil' function.

I think this equipment is now needed as when I fire the boiler up it responds 50% of the time as it should, and other times engages the cut out switch. There are ways around it but is not ideal for timer programmes.

So, my questions are these:-
1. Would you imagine this work should be included as part of the price paid, considering the work description above.
2. If the work was deemed extra, what would be the charge for purchasing the item and installing it.

I am going to chat to the installer but would like a little knowledge first.

Many thanks as always