The actual speeds for ADSL2+ services will vary due to many factors including distance from the local telephone exchange, the quality of the customer's copper phone line, cabling and equipment.
Devices connected by Wi-Fi may experience slower speeds than those connected by Ethernet cable.
We'd recommend having a read of this community article, which may help you check if the speed you're getting at the moment is within acceptable range.
This also includes troubleshooting on how the speed can be improved.
Let us know if we can be of further assistance.