Slow nbn speed

[Kelburn44]

I have had nbn for a month my previous download speed was around 90 now only 25/30 telstra tell me due to congestation and give me a credit I would prefer a faster speed I have fibre yo curb and live in a unit any advice? 

[Jupiter]

It does sound like congestion, which is common in areas where the NBN has only just rolled out as it takes them a few months to adjust the CVC (capacity) orders with NBN Co. It will most likely get sorted out in the background over the next 6 weeks, but if it doesn't improve in the next couple of weeks, contact tech support again and get them to check (you can also run some checks via https://fix.telstra.com)