Mazda 5 starter problem

Hi, apologies if this is a duplicate of other posts - I've searched the site but haven't found anything that matches.

I bought a used Mazda 5 (61 reg) in January 2015. Looove the car, absolutely love it. But over the last couple of months I've experienced difficulty when first starting from cold.

First time I turn the key, it grinds and (mostly) fails to start. Second time it starts fine. When the engine is warm it seems to always start.

I have a 12 month Mazda used car warranty, so I took my car to Motorlux Mazda in Newbury. I was told "There's no problem, but there are two special batteries which the starter uses, and they're really flat and need replacing. Not covered by the warranty - it costs 250." I asked if the price was comparable to what I would be charged at a non-Mazda place, and they said yes. So I paid up. When I collected the car I discovered they actually meant the main battery. 250 for a replacement battery! This is outrageous. And why on earth would a 3-year-old battery need replacing?? But at least I assumed the problem would be sorted.

Anyway, a few weeks later and the problem is back, and getting worse. The incredibly expensive new battery was obviously not the cause, and hasn't fixed the problem.

Does any of this make any sense to anybody? And if so, please could you give me your thoughts on what might be wrong?

Also - I feel I was misled on the battery front, and wonder whether I have any grounds to demand a refund.

Many thanks in advance.

Welcome to the forum.
Mazda USA handles battery warranty differently than UK apparently. http://mazdausa.com/MusaWeb/displayPage.action?pageParameter=ownersWarranty

If the problem went away (at least temporarily) with a new battery, then I would still venture to say that the battery or charging system is the cause. In USA 3 years free replacement is what we have, can't say what they give there, but it would behoove you to look at your warranty manual and return to the dealer with information. They checked the health of the battery the first time, so they can certainly repeat that. If the battery is simply getting depleted, then the charging system needs to be checked, we can get that free in the USA at most auto parts stores, but if you're under full warranty still, then the dealer is responsible for repairs.

What does 2 special batteries mean?
What does 61 reg mean?

Sounds like "blinker fluid" or "muffler bearings" to me. Of course this is probably a diesel, so the twin batteries thing could be true....

In Europe we have a 2.0L petrol with iStop engine ( 150 cv ). 2 small battery ( 1 for star and stop function ).Definitive 2012+ model CW .

For fatboyhuston : normally if the battery is the problem , you see the yellow light ( i-stop ) blinking.