can commercial bank help customers invest money ?

Yes all the banks offer their own mutual funds and will gladly offer to advise you however, they tend to push funds with high loads, either front or back end and high fees. Typically they try to structure their funds such that the most likely outcome for the consumer would be no better than investing in their guaranteed offerings such as CD's except that the consumer is assuming all the risk with their funds.

My parents recently showed me the mutual funds that Scotiabank had sold them on, decades ago. At first it looks good, shows good growth, has a reasonable asset allocation, has reasonable fund managers but it also had a 6% backend load such that when the money is eventually withdrawn, the net effect will be no better than having invested in GIC's (CD's). Not much I can do about it now except to advise against further contributions to the fund but that's the nature of bank offerings, to extract all the value of investing for themselves.

The one thing that is certain about investing through a fund are the fees and it takes gains that are by no means certain to offset those fees. Your best bet is a no load, low fee total market indexed fund. The only management that needs to be done with an index fund is a periodic rebalance according to a formula. Also, by definition, an index fund will beat half the investors out there. You should just open an account with a discount broker and start with a simple index fund and begin by allocating between the index and cash equivalents.

Stay away from banks & insurance companies for investment products.
The costs are high.
The advice is usually mediocre or self serving.
The products are poor to mediocre.

READ:
Mutual Funds For Dummies

Yes. Citi has financial reps on staff that can assist you with all bank investment products. They no longer own Smith Barney but they will refer you if you ask.