what is your location city wise? If in Lahore, i can refer a guy who does the vacuuming.
First try to force them to vacuum the lines, find user manual of AC online or someone who is already using it, or by going to outlet and ask them that you want to see user manual. In that manual, under installation chapter, it should be mentioned that it needs to be vacuumed. In my orient AC, it is mentioned but i hope it is mentioned in haier manual too. B y showing them the line, you can force the outlet/authorized technicians to vacuum the line.
This is nothing but bullcrap! yes pipes come with plastic plugs but they do not seal it. It is only plugged so that physical impurities do not enter the pipe. These plugs cannot keep it under a vacuum lol. Ask yourself/them: When you remove those plugs and connect one side to indoor unit and other side to outdoor unit, in this procedure, how come the pipes remain sealed? Air and moisture will enter the pipes while you are making connections. Its common sense no logic required. These so called techs do only what they have been told by their ustaad g's. They say big words k hamne bary AC lagae han 3 3 saal se koi masla nahi aya (take note that warranty of compressor in these chinese ACs are 3 years) If you do not get it vacuumed, then life of compressor will be very short
No need to find a company as they will charge you much higher, if within 1000-1500 then its fine. Tell them you only want to get it vacuumed, not full installation. Ask around AC repair shops and get a guy who has a vacuum pump.
My suggestion is to get the AC installed from haier techs (as its free). Tell them to do all the fitting and connection of pipes BUT DONT RELEASE THE GAS YET. Contact someone with vacuum pump and ask them that AC is fitted and you only need to vacuum the lines and release the gas. This will take only half hour. Warranty is not voided or anything by just releasing he gas because the vacuum port is already provided on outdoor unit. No need to remove pipes to vacuum it. He will just put his vacuum pump on the port and vacuum it for 30mins then release the gas. Make sure it is vacuum pump, not compressor.
You can coordinate with vacuum guy in advance like e.g. if you have given time to haier techs at 3pm, then give time to vacuum guy at 7-8pm