Another one with Wordpress install issues

[#1]

Apologies.
I really don't understand why there are so many hoops to jump through to get Wordpress working on Plusnet.
I used to host Wordpress on my plusnet account approx 5 years ago, I remember it was tough to get working then. I later disabled it as I needed the disk space.
I decided to reactivate mySQL and have a clean start recently so my wife can do some blogging.
I started by deleting all the files on CCGI and copied over Wordpress again. I pointed my own domain name to that particular webspace. So far so good it seems.
I changed the config files within Wordpress to reflect the details on Plusnet (I double checked these login details/ server name/ password with Plusnet and they confirm they are all correct).
I changed the permissions on the files and folders to 755. (I'm not sure if I have done this correctly as I am using an app called Transmit on the Mac and it's not immediately clear what the permissions on each file is until you click on their properties)
I run the install file and I get this error message:
Error establishing a database connection
This either means that the username and password information in your wp-config.php file is incorrect or we can't contact the database server at rumpus. This could mean your host's database server is down.
* Are you sure you have the correct username and password?
* Are you sure that you have typed the correct hostname?
* Are you sure that the database server is running?
If you're unsure what these terms mean you should probably contact your host. If you still need help you can always visit the WordPress Support Forums.
Can anyone help? I've been back and forth with plusnet tech support for 2 weeks now. Would really hope to get this working.
Many thanks,
CK

[#2]

Are you able to login to phpMyAdmin at mysql.plus.net?
Gabe

[#3]

hi gabe,
thanks for your assistance.
to answer your question.
no.
so something wrong with my login details then despite plusnet tech support say they are correct?

[#4]

It does sound like it.
If the ticket system's proving unsatisfactory, perhaps one of the good folk from Plusnet who occasionally trawl this forum could take a look for you 
(For form's sake, I should give my usual polemic against the use of 755 permissions, but that can wait.)
Gabe

[#5]

Silly question perhaps, but you have used the MySQL password provided by email for that server, and not the one for your account? and the username is your account name on its own, not followed by @ anything?

[#6]

the login details i am using were provided by plusnet to me under the email titled "Database Creation details"
the details look something like this:
The Details of your MYSQL database account are as follows:
MySQL Host: rumpus
Username: XXXXXXXX
Password: XXXXXXXXXXXXXXXXX
DB Name: XXXXXXXX
the number of Xs do not reflect the number of characters in the string.

[#7]

Yes, that's the correct source and format.

[#8]

Thanks everyone for their input in resolving this matter, I thought Plus Net had given up helping me so you guys are the real heroes.
It turns out that the original password I was supplied doesn't work and I have now been assigned a new one. All is well. I'm sure the wife will be happy to finally start blogging!