Can anyone speak Swahili?

Question

Can you tell me how to say "Hi. Thank you so much for writing back"

Thank you!

Answer 1

I don't know how to say "writing back", so I'll translate
"Hi. Thank you very much for your reply", which means
nearly the same thing.
Jambo!
Asante sana kwa jibu lako.

Jambo = Hello!
Asante = thank you
sana = very, very much
kwa = for
jibu = answer, reply
lako (derived from _ako) = your.

Answer 2

Depends on what age group you are trying to reach.

IF its an older person; Jambo, asante sana kwa jibu lako.
A younger person; Vipi asante kwa jibu lako.

Hope this helps