You are, of course, quite right, but these days the services offered by banks are not as personality based as they used to be and with interest rates so low any financial incentive is useful.
To add to my disappointment with Santander.... I filled in their on-line complaints form and have not had any response after two weeks. I then complained to them about their failure to respond to my complaint and, again, no response at all.
I at least hoped that they would acknowledge my correspondence.... Oh well.
It makes me want to reconsider the fact that my business accounts are with them, maybe rather than attract a customer they could end up losing one.

This is far from the first time that Santander have made big promises on the posters in the window then found some reason not to keep the promises inside the branch. My opinion is that you are better banking with someone who can manage to attract customers by being honest and by offering good customer service rather than with a bank that needs gimmicks such as this to get customers.

I was tempted to move my current account from Halifax to Santander and take advantage of their incentive package intended to encourage switching.

In my view I qualified for the full incentive package of £300
£100 for switching my current account
£100 bonus because I already had a Santander residential mortgage
£100 because I would also open a savings account and deposit £10000

While filling in the forms I had a simple query about one entry and telephoned Santander customer services for advice. During the conversation they asked me for details of my mortgage, kept me on hold for several minutes, and then advised me that I only qualified for the basic £100 incentive as my mortgage (taken out in Feb 2010) was with Alliance and Leicester (who are wholly owned by Santander). That also disqualifies the third incentive.

In my view I fulfil the necessary condition "you held a completed Santander residential mortgage on 31 October 2011"
In their view my mortgage is with A&L even though it is owned by and re-branded as Santander and Santander appears on the statements.

It does not give me much confidence in Santander. Needless to say, I shall not be going through the hassle of switching accounts.