With current battery component materials, beyond 2300 mah, the object would become cumbersome.
Article sold by a third-party seller but delivered by Amazon.com which the customer service again, without going into details, demonstrated professionalism entirely made out of the ordinary, all within a few hours even after sending an email to them.
Amazon (as Amazon.com Amazon.co.uk for those that I know) are recommended more than any other online sales site, primarily for their customer service probably among the best in the world.
Additionally exists says service "guarantee A to Z" which I however have never had to resort again, which is a good sign. and I only work either directly or indirectly, or have Amazon shares or other interests. I just want you avoid bad experiences I've had with other competing websites, really rotten for some (all are not true). Do some research on Google for example with a few keywords, and see for yourself.
A word ...