OP i think your phone is the problem that's why you ask this question so i recommend to buy new phone because mercatox is not that mobile friendly like even your phone is really fast still if you click setting or wallet in mercatox we can experience some slow after that so what if your phone is really slow like if this old version of mobile phone then still i recommend this in many trading site here and this is really good for beginners or newbies here in crypto trading another thing i think don't post please
Here some links with some related post about mercatox and this is very useful:
https://bitcointalk.org/index.php?topic=4598962.msg41602682#msg41602682https://bitcointalk.org/index.php?topic=4518011.msg40771811#msg40771811He wont need to purchase a new phone just for the sake of enabling him to use mercatox. They dont have android or ios app which normally you would browse it up with your phone browser.
Unlike on having an app which is somehow convenient on users side.
@OP have you seen on the links given above regarding mercatox issues? If you would read it up you will surely have doubts on using them.Good luck