please explain to me, a formal letter

I received a letter from a cooperator. She wrote:"We do have a number of labs who have agreed the cost of this service with our organization for their sample to be sent by direct courier.The courier company's that we use are .... Please let us know if you wish to use a direct courier service....."

I wonder if the first sentence indicates that: if we change the method the samples be sent into direct courier, we will have to pay for the service on our own?

Should I reply that:" We would love to change the method that is used to send the samples", or " We agree to use the direct courier service", or " As you pointed out, we find that direct courier has many advantages compared to the method we used in the past, thus we decide to use this service". Which way is better?

By the way, I don't understand why she use ' the courier company's ...are '? Is this a native speaker's way of writing?

Thanks in advance