Dave made a very interesting point; why wasn't someone like the OP "brand loyal?" The OP had a previous, very good, experience with another brand.
Well I think Mahindra and several other brands (e.g. LS) know that, for a segment of the buyers, UPFRONT cost/value holds the vast majority of influence on purchase. And value is defined as purchase price compared only to qualities that are easily quantified on an excel spreadsheet.
So, if you are Mahindra and competing for this market segment, all the marketing department has to do is create a spreadsheet of competitors tractors with things like FEL capacity, HP, and turning radius, and a long (but extremely limited warranty. Then take this list to R&D and say "make us a tractor that at least meets the competition on most of these specs, quality/reliability only needs to meet X threshold levels". They can then price the unit 10% less than the competition.
This "formula" will sell X number of tractors regardless of the rest of the picture.
Everything else the company does only has to meet minimum "threshold" levels. Dealer support doesn't matter. Parts availability doesn't matter. Reliability after 5yrs, warrenty fufilment, quality control... None of these things matter much.
Putting resources into these other services cost money. If Mahindra devoted resources to these things (like calling a customer back or expidited shipping) then it would have to raise tractor prices.
Upfront cost should matter so you can't blame the OP for changing. I'd be beyond frustrated too but when you buy the premium you pay for one of the big 'two' is not just for the "name." You also get the other resources they have invested in. Regardless, this is your livelihood and Mahindra should be ashamed.
Also, please don't think I'm suggesting that this type of thing can't happen with "premium" brands (it does) but I think anyone would be hard pressed to suggest that it is nearly as freguent (especially as a percent of units sold!).
Just my thoughts...