Landlord enforcing to pay bill via insecure online profile

I am renting an apartment in South California. The complex got new owner and in the past few months they are sending notes that "ownership prefers" we pay our rent online. For paying with debit or credit card they charge extra service fees. No fees are applied for transactions directly via bank account. My first question is; are they allowed to charge us the service fees for transactions on those payments?

Online profile account only allows to make payments with stored bank account or card information. At the same time, online residents' account numbers are printed on utility postcards we receive via mail and as such they publicly distributed. I find this a breach of security of their online page and I feel unconformable to store any banking information on that profile. So my question is, can they force me to stop paying my rent by check?

Thank you for any help or advice!

 

Thank you both for your responses.