Server changes after a few matches, resulting high ping, requiring reopen battlenet

i play in india
i usually have 100-115ms ping i connect to gmec2 server
recently for the past week the ping after 3-4 matches reaches 140-150ms i connect to gsg1 or ams1 server.
please let me know how to stop this automatic server switching, it is tiny bit annoying having to close the game and battlenet, just closing the game does not fix this issue.