FTP won't work

[#1]

Hi
I've been using orange for the last many years since it was freeserve, just switched to plusnet and immediately I cannot ftp to any of the many websites I maintain.  Logging on to a remote server which doesn't use plusnet and all works fine, just any connection through plusnet and teh ftp is rejected either through the windows ftp, right through to using Dreamweaver.
So far the only response from plusnbet support has been as if I am dealing with a connectivity problem, I'm not and am getting very worried as maintaining websites is my work. Switching to plusnet - which was so I could get a static IP, has so far been a disaster and all I have done for whole day is try to find out why ftp isn't working when really I know the problem is not my end.
Has anybody else come across this, the same problem when using both domain name and IP access through plusnet. If anybody from plusnet is looking the error report is  54032775   
Realistically, until ftp is working I don't have a working internet connection! 
Help!

[#2]

Where are the ftp servers you are trying to connect to?
Have you tried with passive mode on and off?
Is the Plusnet firewall turned off? https://portal.plus.net/my.html?action=firewall (if you change this you have to reconnect for it to take effect)

[#3]

Hi Jelv
Firewall on router and on plusnet (as per your link) already turned off and yes, had tried passive ftp.
The servers are a couple of VPSs on Hostinguk
eg if I use filezilla.  This is the result when accessing from a remote server - not the one that has the web site

Status: Resolving address of pesticide-residue-testing.co.uk
Status: Connecting to 79.171.35.114:21...
Status: Connection established, waiting for welcome message...
Response: 220 Microsoft FTP Service
Command: USER xxxxxx
Response: 331 Password required for pesticides.
Command: PASS *********
Response: 230 User xxxxx  logged in.

But this is the result when used locally (through plusnet connection)

Status: Resolving address of pesticide-residue-testing.co.uk
Status: Connecting to 79.171.35.114:21...
Status: Connection established, waiting for welcome message...
Response: 530 Connection refused, unknown IP address.
Error: Critical error
Error: Could not connect to server

Any thoughts gratefully received

[#4]

here's a thought. I've got a new static IP.  Is the unknown IP address mine?  ie the hosting server is saying I don't know you, go away!

[#5]

Yes, it looks like the remote FTP server has a whitelist of allowed IP addresses.

[#6]

Resolution!
There was a white list and my IP is now on it. 
Hoepfully this will be a useful serie sof posts if somebody else gets this problem. I can see the use of white lists growing.
Now to get back to work.