American Musical Supply Company won't honor their "free extended warranty" Internet

 American Musical Supply does not honor their 1 year free extended warranty!
I bought a Bugera v22 combo amp form them in January 2014 which means I get the manufacturers warranty of 1 year and their extended warranty of a second year.
I have until January 2016 to get my amp in for any repairs necessary.
I called them and they gave the address to send it in as it has intermittent bad tube sockets. I know this as I can put other new tubes in and it does the same thing and if you push on the tube it will come off or on. anyway when I called since I have to pay for the shipping to their repair dept. I ask if I could just take the amp section out and send this to them which would save me a lot of shipping money small package (11 lbs for head alone versus 45 pounds for combo amp and a huge box) They told me no I can't do that it has to be the whole unit so I told them I don't know why when it is just the amplifier that's bad and that the speaker is a different speaker than the one that came with. With that they told that it isn't covered under the warranty because I changed the speaker as does most semi and professional musicians who have a favorite speaker. I told him that no where on their website when you buy an item from them does it state can't change speaker which is 2 wires to the speaker that it would void the warranty. they are sticking with this and my amp will not be fixed by them. I ran this past the call center supervisor and a VM to his manager and they will do nothing. Their extended warranty is not legitimate without a disclaimer about changing speakers or even tube out which  most serious musicians will do.