dogged determinedness

“Dear Rodney, I just wanted to say a personal thank you for all your help with our premises lease.  You managed to turn a very strenuous and long winded process with our Landlord into something achievable.  We will never forget your dogged determinedness on Christmas Eve to get us into the premises so we could use the Christmas period to move all our equipment in, ready to start the New Year, you really went the extra mile.  I wouldn’t hesitate to recommend your company to anyone, thank you!”