OnePlus India — oneplus 2. attachments not getting downloaded

Address:

Kolkata, West Bengal, 700012

I have been using one plus 2 from last almost 2 yrs. Last six to eight months experiencing a typical issue of attachments not visible at the time mail is downloaded. It shows after many refreshments r done again and again. At times it takes few days to actually display the attachment sent with the mail by the sender.

Kindly suggest remedy or will have to stop using this phone.