Singular and plural nouns in one sentence

The word "treatment" is used in its uncountable aspect because the writer is concerned with treatment in general in this particular sentence; of course, it is quite possible that several sorts of treatment are available and if the discussion comes to the point of giving information about a given one, then the indefinite article "a/an" can still be used and you can also speak of that particular treatment as treatment in general. In the case of the plural of "payment" I think that there is no question at all of a variety of payments but simply a reference to the fact that payment is made on the basis of eligibility and therefore must be monthly or weekly, which entails that each small monthly or weekly allowance is a payment, thereby, speaking of all of them together, the need to use a plural.