Due to/As the result of CHT promotion, business network bandwidth is upgraded ( in our company ) but the price goes down instead. ( The price is decreased by NTD$876 )
*Business mostly use business network instead of residential one, therefore, just call it business network bandwidth.
*You do not have to translate word by word from Chinese to English. By logic, if something is upgraded, it means higher price. Therefore, just use "but" and "instead".
*Your translation is different from what you meant in Chinese.
In Chinese, you did not specify that your company need to upgrade the network bandwidth.
Your English Translation,
**you have word order and logic issue in your translation
There is always not a "need" when there is a promotion. You upgrade something as a result of certain promotion, that is not a need but an opportunity. If you have said "We need to lower down/reduce our network bandwidth cost so that we take the promotion." ,then that is a need.
So you can say
"We upgraded our network bandwidth in our company (the price is decreased form NTD1,875 to NTD999 as the result of CHT promotion).
*As a result and As the result
use "the" if you want to emphasize the result of that promotion
use "a" if you are describing a general result of that promotion
Based on your Chinese sentence, you are emphasizing the reuslt of that promtoion, therefore, use as the result of.
2014-10-16 07:38:12 補充：
Change the typo
the price is decreased "form"
the price is descreased "from"
***I copied and pasted partial translation of yours.
2014-10-16 14:55:27 補充：
Good job, Nathan,
However, to be more specific
Due to a/the recent promotion, CHT has offered/is offering to upgrade (our) broadband/braonetwork bandwidth without escalating prices/escalating the price/price escalation.
"I would prefer to use "has offered" or is offering here.
2014-10-16 15:30:50 補充：
Nathan's answer is a bit ambiguous. It indicated that CHT upgraded all its network by providing broader band without a price increase. For example, Verizon "upgraded most of its own networks" from 3G to 4G and offered a free upgrade to all its customers.